This invention relates to wheelchairs and, in particular, to a wheelchair for use in a controlled environment. By "controlled environment" is meant any area in which the production, spread or release of contaminants is prevented or minimized. Contaminants can be animate or inanimate, e.g. bacteria or particles of dust.
There are many occupations or tasks which must be performed in a controlled environment. The "cleanroom" used for the production of semiconductor wafers is an early but by no means the only example. Research and production in the electronic, aerospace, optical, recording, pharmaceutical, bio-tech, and medical industries must be done under strictly controlled environmental conditions. A cleanroom environment requires that particles not be generated, spread, or released in the cleanroom. In many applications, e.g. bio-tech, genetic engineering, and nuclear, the environment is controlled as much to keep contaminants in as it is to keep them out.
There is a problem in that many qualified, highly trained people cannot enter a cleanroom because cleanrooms typically do not permit wheelchair access. With at least 9,000 cleanrooms in the United States alone, this represents a significant restriction on people whose mobility is impaired.
Wheelchair access to a cleanroom is not simply a matter of scrupulously cleaning a wheelchair and placing it in a cleanroom. The tires, wheels, frame, and seat all retain or generate a large number of particles. The moving parts of a wheelchair generate particles and the tires pick up particles from the floor, particularly the rear wheels which can bring contaminants from the floor up to desk height. A wheelchair, especially the seat and back, can accumulate a static charge and attract particles and lint, perhaps also causing problems for the occupant, or a product being handled, when a grounded surface is touched.
A wheelchair suitable for a cleanroom is also suitable for aseptic environments such as hospitals. A wheelchair is widely recognized as a source of infection in hospitals. For example, the Health and Safety at Work Act in the United Kingdom establishes national guidelines for cleaning hospital wheelchairs. However, modern wheelchairs are typically complex mechanisms that are difficult to clean even when disassembled. A wheelchair for a cleanroom must be easy to clean and, therefore, is particularly suited to hospital use as well.
When not in use, a wheelchair takes up a considerable amount floor space, requiring a large vestibule adjacent a cleanroom. While there are many techniques for folding a wheelchair, the wheelchairs of the prior art typically have a large number of joints and adjustment holes, each of which can trap or produce particles. In addition, the interconnected braces obstruct the space underneath the seat.
In the prior art, it is known to provide brushes adjacent the wheels of a wheelchair to remove dirt adhering to the wheels, e.g. U.S. Pat. Nos. 2,740,643--Gordon and 4,605,239--Warfel. However, the wheelchairs described in these patents are unsuited for controlled environments because the dirt removed is macroscopic, e.g. mud from outdoors. The brushes would accumulate and shed large quantities of dust in a cleanroom.
In view of the foregoing, it is therefore an object of the invention to provide a wheelchair for controlled environments.
Another object of the invention is to provide a cleanroom wheelchair which can be stored relatively flat.
A further object of the invention is to provide a cleanroom wheelchair having a small surface area.
Another object of the invention is to provide a wheelchair which is easily cleaned and is suited to automated cleaning.
A further object of the invention is to provide an anti-static wheelchair for controlled environments.
Another object of the invention is to provide a cleanroom wheelchair having protective apparel attached to the chair.
A further object of the invention is to provide a wheelchair in which the sides, front and back form a parallelogram for folding and storage.
Another object of the invention is to provide a folding wheelchair having a large carrying space underneath the seat.